Carbon has traditionally been the most common material of choice for polymer electrolyte fuel cell (PEFC) electrocatalyst supports due to its low cost, high abundance, high electronic conductivity, and high Brunauer, Emmett, and Teller (BET) surface area, which permits good dispersion of platinum (Pt) active catalyst particles. However, the instability of the carbon-supported platinum electrocatalyst due at least in part to carbon corrosion is a key issue that currently precludes widespread commercialization of PEFCs for automotive applications.
The adverse consequences of carbon corrosion include (i) platinum nanoparticle agglomeration/detachment; (ii) macroscopic electrode thinning/loss of porosity in the electrode; and (iii) enhanced hydrophilicity of the remaining support surface. The first results in loss of catalyst active surface area and lower mass activity resulting from reduced platinum utilization, whereas the second and third result in a lower capacity to hold water and enhanced flooding, leading to severe condensed-phase mass transport limitations. Clearly, both consequences directly impact PEFC cost and performance, especially in the context of automotive stacks.
To address the issues with carbon-based catalyst, non-carbon alternatives are being investigated. However, non-carbon alternatives are typically more costly, and conventional catalyst structures continue to allow leaching, agglomeration and corrosion of the catalyst materials.